Adhesion of rubber to metal or organic or inorganic fibers has, for a long time, been the subject of considerable experimentation and research. Various solutions have been suggested and have provided various degrees of success.
For example, various physical configurations of cables wire filaments have been used to enhance physical or mechanical adhesion to rubber. Also, the surface of wire filaments has been treated by various materials and methods to enhance adhesion to rubber. Further, various materials have been mixed with the rubber itself in an effort to increase its adhesion to a cord of cabled wire filaments or organic fiber filaments.
In one aspect, boric acid, orthoboric acid, lead borate, sodium borate, and cobalt borate have been taught to be useful for aiding in the bonding of rubber to brass, bronze, iron, aluminum, and titanium. For example, see British Pat. No. 1,338,930.
Such rubber-metal reinforced composites are often applicable to tires, industrial belts and hose.
However, methods of enhancing adhesion of rubber to filament reinforcement are still being sought.